A: Investors have all sorts of bad habits. It's hard to pick just one.

But it seems the one fault that's pretty common that leads to a host of missteps, is acting on personal hunches. Chasing guesses about the future of stocks leads investors astray not only in the types of investments they buy, but also the timing of those purchases.

Regarding investment selection, it's incredible how many investors bet their portfolios on good things they heard about a company from a friend. Chasing individual stocks is risky business to begin with, and going so on just a feeling that a company is doing well rarely ends in a good way.

But almost as bad is an investor who "has a feeling" that stocks are going to go up or down in the next few weeks, leading to postponed decisions. Investors who are able to time the market on a routine basis are so rare, it's almost safe to say they don't exist.

Hunches consistently distract investors from what really matters: creating a portfolio with the expected returns and risk that matches an investors' goals. Anything else is just a distraction.